The present invention relates to methods and apparatus for supplying municipal solid waste (MSW) and/or other types of solid waste comprising both organic (i.e. carbonaceous) waste material and inorganic waste material into a plasma gasifier reactor (PGR) in which the solid waste is processed to form a syngas (i.e. a gas comprising hydrogen, carbon monoxide and carbon dioxide) from the organic waste material and a molten slag from the inorganic waste material. In particular, the invention relates to feed apparatus for feeding solid waste into a plasma gasifier reactor, to solid waste processing apparatus comprising said feed apparatus and said plasma gasifier reactor, and to methods of feeding solid waste into a plasma gasifier reactor and processing solid waste to produce a syngas and a slag.
MSW, often colloquially referred to as trash, garbage, refuse or rubbish, can be disposed of in a variety of ways, including being used as landfill, or being processed via combustion, pyrolysis, gasification or plasma gasification so as to generate energy and/or useful chemicals.
The technique of plasma gasification has a number of benefits in terms of dealing with such forms of waste. In the gasification reaction the organic waste material present in the solid waste is gasified to produce a syngas via heating the waste material in environment that leads to gasification rather than combustion of the organic material (specifically, in an environment in which the oxygen concentration is not sufficient for combustion to take place). In plasma gasification one or more plasma torches (also referred to as plasma arc torches) are used to generate one or more plasma jets inside the PGR vessel that subject solid waste in the gasification zone of the PGR vessel to intense heat (with temperatures in excess of 2000° C. in the gasification zone being readily achievable via this method). The thermal energy supplied by the plasma torches to the solid waste is sufficient to gasify the organic waste materials (i.e. convert the organic waste materials into syngas) with high efficiency and to convert the inorganic waste materials into a molten slag. In this way, a high level of conversion of the organic waste material to a syngas can be achieved, whilst preventing the production of toxic and/or environmentally harmful species (such as furans, dioxins, NOx and SOx) that might otherwise result if the material were to be combusted. The syngas can then be separately combusted to generate electrical power and/or can be used in further processes (such as the Fischer-Tropsch process) to generate useful chemicals, while the molten slag can be cooled to provide a cooled, inert slag that can be disposed of with greater ease and safety than the original waste material.
A number of plasma gasification processes and PGRs are known and have been described in the art, such as for example those described in US2010/199556A, US2010/199560A, US6155182A, WO2008/011213A, US2012/121477A, US2009/064581 A and US2012/121468A, the contents of which are incorporated herein by reference.
Nevertheless, alternative and improved methods and apparatus for processing MSW and other such types of solid waste via plasma gasification, and in particular alternative and improved methods and apparatus for feeding such waste into a plasma gasifier, are desired.